Configuring a network of devices to operate within a television whitespace spectrum

ABSTRACT

Nodes within a network are configured to communicate with one another on one or more television white space (TVWS) frequencies that may be subject to interference caused by nearby TV towers. In order to mitigate that interference, the nodes may be configured to communicate according to specific operating parameters. The operating parameters may be generated based on expected interference levels caused by the nearby TV towers or QOS metrics associated with available channels. The nodes may also update a private database to reflect the expected interference levels or measured QOS metrics for different channels.

BACKGROUND OF THE INVENTION Field of the Invention

Embodiments of the present invention relate generally to wirelessdigital communication and, more specifically, to configuring a networkof devices to operate within a television whitespace spectrum.

Description of the Related Art

Television white space (TVWS) devices are wireless devices configured tooperate within white space frequency bands associated with thetelevision frequency spectrum. Under various circumstances, TVWS devicesmay be exposed to high levels of interference from TV towers, therebyimpairing the capacity of the TVWS device to transmit and/or receivedata effectively.

For example, if a TVWS device resides sufficiently close to a TV tower,then transmissions generated by the TV tower may interfere with datacommunications associated with the TVWS device. Alternatively, if a TVWSdevice communicates on a frequency that is sufficiently close to afrequency used by the TV tower, then transmissions generated by the TVtower may likewise interfere with communications associated with theTVWS device. These two factors may also compound one another, and so insituations where TVWS device resides close to a TV tower and alsocommunicates on a frequency used by the TV tower, that TVWS device mayexperience very high levels of interference.

The issues described above are especially problematic when TVWS devicesoperate as nodes within a network and are configured to interoperatewith each other to support operation of the network as whole. If TVtower interference impairs the ability of the TVWS devices tocommunicate with one another, then the interoperation of those devicesmay be likewise impaired, and, consequently, the overall operation ofthe network may suffer.

As the foregoing illustrates, what is needed in the art is an improvedtechnique for configuring devices that operate within a TVWS spectrum.

SUMMARY OF THE INVENTION

One embodiment of the present invention sets forth acomputer-implemented method for configuring a node to communicate on atelevision white space (TVWS) spectrum of frequencies, includingreceiving a request for at least one operating parameter from a firstnode that resides at a first location in a network, retrieving one ormore entries associated with the first location from a first database,where each of the one or more entries reflects a quality of servicemetric for a TVWS channel at the first location, determining the atleast one operating parameter for the first node based on the one ormore entries, where the at least one operating parameter indicates afirst TVWS channel, and transmitting the at least one operatingparameter to the first node, where the first node is configured toperform future communication operations over the first TVWS channelaccording to the at least one operating parameter.

One advantage of the disclosed approach is that a network of nodes isconfigured to perform wireless communications within a TVWS spectrumdespite interference that may be caused by nearby TV towers.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 illustrates a network system, according to one embodiment of thepresent invention;

FIG. 2 illustrates a network interface configured to transmit andreceive data within the wireless mesh network of FIG. 1, according toone embodiment of the present invention;

FIG. 3 is a block diagram that illustrates the server of FIG. 1 ingreater detail, according to one embodiment of the present invention;

FIG. 4 is a conceptual diagram that illustrates a portion of thewireless mesh network of FIG. 1 that is subject to interference causedby a TV signal, according to one embodiment of the present invention;

FIG. 5 is a conceptual diagram that illustrates a graph of power versusfrequency for the TV signal of FIG. 4, according to one embodiment ofthe present invention;

FIG. 6 illustrates various graphs that reflect estimated signalattenuation of the TV signal of FIG. 4, according to one embodiment ofthe present invention;

FIG. 7 is a conceptual diagram that illustrates an exemplary table in anoptimized database shown in FIG. 4 that includes quality of servicemetrics for channels on which the nodes of FIG. 4 may communicate,according to one embodiment of the present invention;

FIG. 8 is a flow diagram of method steps for estimating the level ofinterference caused by the TV signal of FIG. 4, according to oneembodiment of the present invention;

FIG. 9 is a flow diagram of method steps for updating the optimizeddatabase of FIG. 4 to reflect quality of service metrics received fromone of the nodes of FIG. 4, according to one embodiment of the presentinvention; and

FIG. 10 is a flow diagram of method steps for reconfiguring one of thenodes of FIG. 4 to mitigate the interference caused by the TV signal ofFIG. 4, according to one embodiment of the present invention.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth toprovide a more thorough understanding of the present invention. However,it will be apparent to one of skill in the art that the presentinvention may be practiced without one or more of these specificdetails. In other instances, well-known features have not been describedin order to avoid obscuring the present invention.

System Overview

FIG. 1 illustrates a network system 100, according to one embodiment ofthe present invention. The network system 100 includes, withoutlimitation, a wireless mesh network 102, which may include a source node110, intermediate nodes 130 and destination node 112. The source node110 is able to communicate with certain intermediate nodes 130 viacommunication links 132. The intermediate nodes 130 communicate amongthemselves via communication links 134. The intermediate nodes 130communicate with the destination node 112 via communication links 136.The network system 100 may also include an access point 150, a network152, and a server 154.

A discovery protocol may be implemented to determine node adjacency toone or more adjacent nodes. For example, intermediate node 130-2 mayexecute the discovery protocol to determine that nodes 110, 130-1,130-3, and 130-5 are adjacent to node 130-2. Furthermore, this nodeadjacency indicates that communication links 132-2, 134-2, 134-4 and134-3 may be established between the nodes 110, 130-1, 130-3, and 130-5,respectively. One skilled in the art will understand that anytechnically feasible discovery protocol may be implemented withoutdeparting from the scope and spirit of embodiments of the presentinvention.

The discovery protocol may also be implemented to determine the hoppingsequences of adjacent nodes, i.e. the sequence of channels across whichnodes periodically receive payload data. As is known in the art, a“channel” may correspond to a particular range of frequencies. Onceadjacency is established between the source node 110 and at least oneintermediate node 130, the source node 110 may generate payload data fordelivery to the destination node 112, assuming a path is available. Thepayload data may comprise an Internet protocol (IP) packet, an Ethernetframe, or any other technically feasible unit of data. Similarly, anytechnically feasible addressing and forwarding techniques may beimplemented to facilitate delivery of the payload data from the sourcenode 110 to the destination node 112. For example, the payload data mayinclude a header field configured to include a destination address, suchas an IP address or Ethernet media access control (MAC) address.

Each intermediate node 130 may be configured to forward the payload databased on the destination address. Alternatively, the payload data mayinclude a header field configured to include at least one switch labelto define a predetermined path from the source node 110 to thedestination node 112. A forwarding database may be maintained by eachintermediate node 130 that indicates which communication link 132, 134,136 should be used and in what priority to transmit the payload data fordelivery to the destination node 112. The forwarding database mayrepresent multiple paths to the destination address, and each of themultiple paths may include one or more cost values. Any technicallyfeasible type of cost value may characterize a link or a path within thenetwork system 100. In one embodiment, each node within the wirelessmesh network 102 implements substantially identical functionality andeach node may act as a source node, destination node or intermediatenode.

In network system 100, the access point 150 is configured to communicatewith at least one node within the wireless mesh network 102, such asintermediate node 130-4. Communication may include transmission ofpayload data, timing data, or any other technically relevant databetween the access point 150 and the at least one node within thewireless mesh network 102. For example, communications link 140 may beestablished between the access point 150 and intermediate node 130-4 tofacilitate transmission of payload data between wireless mesh network102 and network 152. The network 152 is coupled to the server 154 viacommunications link 142. The access point 150 is coupled to the network152, which may comprise any wired, optical, wireless, or hybrid networkconfigured to transmit payload data between the access point 150 and theserver 154.

In one embodiment, the server 154 represents a destination for payloaddata originating within the wireless mesh network 102 and a source ofpayload data destined for one or more nodes within the wireless meshnetwork 102. In another embodiment, the server 154 executes anapplication for interacting with nodes within the wireless mesh network102. For example, nodes within the wireless mesh network 102 may performmeasurements to generate measurement data, such as power consumptiondata. The server 154 may execute an application to collect themeasurement data and report the measurement data. In yet anotherembodiment, the server 154 queries nodes within the wireless meshnetwork 102 for certain data. Each queried node replies with requesteddata, such as consumption data, system status and health data, and soforth. In an alternative embodiment, each node within the wireless meshnetwork 102 autonomously reports certain data, which is collected by theserver 154 as the data becomes available via autonomous reporting.Exemplary details of server 154 are described in greater detail below inconjunction with FIG. 3.

The techniques described herein are sufficiently flexible to be utilizedwithin any technically feasible network environment including, withoutlimitation, a wide-area network (WAN) or a local-area network (LAN).Moreover, multiple network types may exist within a given network system100. For example, communications between two nodes 130 or between a node130 and the corresponding access point 150 may be via a radio-frequencylocal-area network (RF LAN), while communications between access points150 and the network may be via a WAN such as a general packet radioservice (GPRS). As mentioned above, each node within wireless meshnetwork 102 includes a network interface that enables the node tocommunicate wirelessly with other nodes. Each node 130 may implement thefirst and/or second embodiments of the invention, as described above, byoperation of the network interface. An exemplary network interface isdescribed below in conjunction with FIG. 2.

FIG. 2 illustrates a network interface configured to transmit andreceive data within the wireless mesh network of FIG. 1, according toone embodiment of the present invention. Each node 110, 112, 130 withinthe wireless mesh network 102 of FIG. 1 includes at least one instanceof the network interface 200. The network interface 200 may include,without limitation, a microprocessor unit (MPU) 210, a digital signalprocessor (DSP) 214, digital to analog converters (DACs) 220, 221,analog to digital converters (ADCs) 222, 223, analog mixers 224, 225,226, 227, a phase shifter 232, an oscillator 230, a power amplifier (PA)242, a low noise amplifier (LNA) 240, an antenna switch 244, and anantenna 246. A memory 212 may be coupled to the MPU 210 for localprogram and data storage. Similarly, a memory 216 may be coupled to theDSP 214 for local program and data storage. Memory 212 and/or memory 216may be used to store data structures such as, e.g., a forwardingdatabase, and/or routing tables that include primary and secondary pathinformation, path cost values, and so forth.

In one embodiment, the MPU 210 implements procedures for processing IPpackets transmitted or received as payload data by the network interface200. The procedures for processing the IP packets may include, withoutlimitation, wireless routing, encryption, authentication, protocoltranslation, and routing between and among different wireless and wirednetwork ports. In one embodiment, MPU 210 implements the techniquesperformed by the node, as described in conjunction with FIGS. 1 and 3-7,when MPU 210 executes a firmware program stored in memory within networkinterface 200.

The DSP 214 is coupled to DAC 220 and DAC 221. Each DAC 220, 221 isconfigured to convert a stream of outbound digital values into acorresponding analog signal. The outbound digital values are computed bythe signal processing procedures for modulating one or more channels.The DSP 214 is also coupled to ADC 222 and ADC 223. Each ADC 222, 223 isconfigured to sample and quantize an analog signal to generate a streamof inbound digital values. The inbound digital values are processed bythe signal processing procedures to demodulate and extract payload datafrom the inbound digital values. Persons having ordinary skill in theart will recognize that network interface 200 represents just onepossible network interface that may be implemented within wireless meshnetwork 102 shown in FIG. 1, and that any other technically feasibledevice for transmitting and receiving data may be incorporated withinany of the nodes within wireless mesh network 102.

FIG. 3 is a block diagram that illustrates server 154 of FIG. 1 ingreater detail, according to one embodiment of the present invention. Inthis particular embodiment, server 154 comprises a computing devicecapable of processing data by executing program instructions stored inmemory. Server 154 may also more broadly comprise any type of machinecapable of processing data. As shown, server 154 includes, withoutlimitation, a processing unit 302, input/output (I/O) devices 304, andmemory 306. As also shown, processing unit 302, I/O devices 304, andmemory 306 are coupled to one another.

Processing unit 302 may include one or more central processing unit(CPUs), parallel processing units (PPUs), graphics processing units(GPUs), application-specific integrated circuits (ASICs),field-programmable gate arrays (FPGAs), or any other type of processingunit capable of processing data. In addition, processing unit 156 mayinclude various combinations of processing units, such as, e.g., a CPUcoupled to a GPU.

I/O devices 304 may include input devices, such as a keyboard, a mouse,a touchpad, a microphone, a video camera, and so forth, as well asoutput devices, such as a screen, a speaker, a printer, a projector, andso forth. In addition, I/O devices 304 may include devices capable ofperforming both input and output operations, such as a touch screen, anEthernet port, a universal serial bus (USB) port, a serial port, etc.I/O devices 304, as well as processing unit 302 described above, areboth configured to read data from and write data to memory 306.

Memory 306 may include a hard disk, one or more random access memory(RAM) modules, a database, and so forth. In general, any technicallyfeasible unit capable of storing data may implement memory 306. Memory306 includes an application 308 that may be executed by processing unit302 to perform the various functions of server 154 described herein.Persons skilled in the art will recognize that the block diagram shownin FIG. 3 illustrates just one possible implementation of server 154,and that any system or combination of systems configured to perform thefunctionality of server 154 described herein falls within the scope ofthe present invention.

Operating within a TVWS Spectrum

FIG. 4 is a conceptual diagram that illustrates a portion 412 of thewireless mesh network 102 of FIG. 1 that is subject to interferencecaused by a TV signal 402, according to one embodiment of the presentinvention. As a general matter, FIG. 4 includes some of the samecomponents as those shown in FIG. 1; however, certain components havebeen omitted, for the sake of simplicity, while other components havebeen added. As shown, FIG. 4 includes a television (TV) tower 400, node130-7 and node 130-8 (referred to hereinafter collectively as nodes 130,unless otherwise noted), network 152, server 154, a TVWS database 410,and an optimization database 420.

Nodes 130, server 154, authorization database 410, and optimizeddatabase 420 are coupled together via network 152. Nodes 130-7 and 130-8are coupled to network 152 by communication links 430-1 and 430-2,respectively, server 154 is coupled to network 152 by a communicationlink 440, TVWS database is coupled to network 152 by a communicationlink 450, and optimized database is coupled to network 152 by acommunication link 460. Nodes 130-7 and 130-8 are also coupled to oneanother by a communication link 134-8.

Nodes 130 are configured to interoperate with each other and toparticipate in the overall operation of wireless mesh network 102. Indoing so, nodes 130 are configured to perform data communications onchannels associated with TV white space (TVWS) spectrum frequencies.Nodes 130 may communicate on a channel corresponding to a particularTVWS frequency, or may implement a frequency hopping sequence within achannel corresponding to a given range of TVWS frequencies. Nodes 130may interact with server 154 in order to determine one or more specificTVWS channels on which to communicate. Server 154 may, in turn, accessTVWS database 410 in order to determine the TVWS channels that arecurrently available at the location occupied by nodes 130.

TVWS database 410 is a public database that records available TVWSchannels for different physical locations. The different TVWS channelsavailable for a particular physical location correspond to frequenciesthat are not currently in use by any TV towers proximate to the physicallocation. TVWS database 410 may also record transmitter settings for theTV towers proximate to a given physical location, including atransmitter power and transmitter frequency range. In one embodiment,TVWS database 410 may be implemented by multiple different databaseseach configured to store a different type of data. Server 154 isconfigured to communicate with TVWS database 410, on behalf of nodes130, in order to select a particular channel on which those nodes 130should communicate, as mentioned above and as described in greaterdetail herein. Server 154 may also communicate with optimized database420 in order to retrieve quality-of-service (QOS) metrics for specificchannels.

Optimized database 420 is a private database that records QOS metricsfor different TVWS channels. Server 154 or nodes 130 may compute QOSmetrics for different TVWS channels based on power loss models, asdescribed in greater detail herein and below in conjunction with FIGS. 6and 8. Alternatively, nodes 130 may determine QOS metrics for differentTVWS channels based on measurements performed while communicating onthose channels. Nodes 130 may then report those QOS metrics to optimizeddatabase 420 by way of server 154, as described in greater detail hereinand below in conjunction with FIGS. 7 and 9-10.

In FIG. 4, node 130-7 resides at a distance 414 from TV tower 400 andnode 130-8 resides at a distance 416 from TV tower 400. At thosedistances, nodes 130 may be subject to interference caused by TV signal402 that is generated by TV tower 400. For example, if distance 414 issufficiently small, then node 130-7 may be subject to interferencecaused by TV signal 402. Nodes 130 may also be subject to interferencecaused by TV signal 402 when nodes 130 communicate on a channel that isclose to a frequency in use by TV tower 400 to generate TV signal 402,as described in greater detail below in conjunction with FIG. 5.

FIG. 5 is a conceptual diagram that illustrates a graph of power versusfrequency for the TV signal of FIG. 4, according to one embodiment ofthe present invention. Graph 500 is described herein for exemplarypurposes only to illustrate the different levels of interference thatmay be caused by TV signal 402 generated by TV tower 400. As shown,graph 500 includes a power axis 510, a frequency axis 520, and a plot530 of power versus frequency. Frequency axis 520 is divided intospecific ranges of frequencies, or channels, including channel 522,channel 524, channel 526, and channel 528. In the exemplary embodimentdiscussed herein, TV tower 400 transmits TV signal 402 on channel 522,while nodes 130 communicate with one another and with server 154 onchannel 524.

The amount of power associated with TV signal 402 should, under idealcircumstances, be limited to just the frequencies associated withchannel 522. However, under normal circumstances, TV signal 402 may alsogenerate power at frequencies extending beyond channel 522 into channels524, 526, and 528, as is shown. Accordingly, nodes 130 operating onchannel 524 may be subject to interference derived from TV signal 402.

Referring back now to FIG. 4, server 154 is configured to mitigate theinterference caused by TV signal 402 by generating an expectedinterference level for each channel that is available to nodes 130 atthe location occupied by nodes 130. Sever 154 may then determine a setof operational parameters for nodes 130 that allow those nodes toeffectively communicate despite the interference that may be caused byTV signal 402. Server 154 may determine similar or different operationalparameters for each of nodes 130. The set of operational parameters mayinclude a variety of different parameters that influence the operationand/or configuration of the nodes 130.

For example, the operational parameters determined for a given node 130could include a selected channel on which to communicate, a particularsensitivity with which to process received signals, a targetsignal-to-noise ratio implemented for a signal to be transmitted, orother parameters that may influence the quality and strength of signalsinvolved with communication with other nodes 130. In one embodiment,server 154 may cause a node 130 to power off in order to conserve powerwhen subject to high levels of interference.

In one embodiment, server 154 may compute the expected interferencelevel for each channel that is available to nodes 130 at the locationoccupied by those nodes, and then select the channel with the lowestexpected interference. Server 154 may also adjust additional operationalparameters to optimize communications associated with the selectedchannel. In another embodiment, server 154 computes the expectedinterference level for a predetermined channel and then adjustsadditional operational parameters for nodes 130 to optimizecommunications associated with the predetermined channel. Server 154 mayalso cause a node 130 to switch channels when the expected interferencelevel associated with that node 130 exceeds a threshold value.

Server 154 may compute the expected interference level at a givenchannel and location based on power loss models that reflect the powerloss of TV signal 402 at the given channel and location. For example,one power loss model may reflect the power that is lost by TV signal 402as a function of frequency separation between TV signal 402 and thegiven channel. Another power loss model could reflect the power that islost by TV signal 402 as a function of physical distance between the TVtower 400 and the node 130. Server 154 could combine these two models tocompute the overall interference level at the given channel andlocation.

In doing so, server 154 may determine the initial transmission frequencyand power level of TV signal 402 (e.g., by communicating with TVWSdatabase 410). Then, server 154 may apply the different power lossmodels mentioned above to identify an amount of power remaining withinTV signal 402 at a specific frequency and at a specific distance from TVtower 400. Two exemplary power loss models are discussed in greaterdetail below in conjunction with FIG. 6.

FIG. 6 illustrates various graphs that reflect estimated signalattenuation of TV signal 402 of FIG. 4, according to one embodiment ofthe present invention. Graphs 600 and 640 are described herein forexemplary purposes only to illustrate estimated power loss of TV signal402 as a function of different parameters.

Graph 600 represents one power loss model that server 154 may implement.As shown, graph 600 includes a power loss axis 610, a frequency axis620, and a plot 630 of power loss versus frequency. For a givenfrequency 622, plot 630 indicates a power loss 612 of TV signal 402.Power loss 612 represents the amount of power that is lost between theoriginal frequency at which TV signal 402 is transmitted, and frequency622. Frequency 622 could be, e.g., a frequency at which the nodes 130may communicate. In one embodiment, server 154 computes the power lossof TV signal 402 as 11.5*(deltaF+3.6), where deltaF is the frequencydifference between TV signal 402 and any channel on which the nodes 130may communicate.

Graph 640 represents another power loss model that server 154 mayimplement. As shown, graph 640 includes a power loss axis 650, afrequency axis 660, and a plot 670 of power loss versus distance. For agiven distance 662, plot 670 indicates power loss 652 of TV signal 402.Power loss 652 represents the amount of power that is lost due topropagation of TV signal 402 between TV tower 400 and the node 130. Thatdistance could be, e.g. distance 414 or 416. In one embodiment, thepower loss model represented by graph 640 corresponds to the Hata lossmodel, the Erceg loss model, or another path loss model.

Server 154 may compute the total power loss of TV signal 402 bycombining the two power loss models. Based on this total power loss, andbased on the initial transmission frequency and power level associatedwith TV signal 402, the node 130 may compute the expected interferencelevel due to TV signal 402 at a given frequency and distance from TVtower 402. In one embodiment, the expected amount of interference iscomputed as: interference=initial power of TV signal 402−power loss dueto frequency separation−power loss due to physical separation.

Referring back now to FIG. 4, sever 154 is configured to compute theexpected interference level caused by TV signal 402 for a set ofavailable TVWS channels by implementing the techniques described abovein conjunction with FIG. 5. Server 154 may then determine operatingparameters for nodes 130, including a channel on which those nodes 130should communicate, and transmit those operating parameters to nodes130. Nodes 130 may then communicate with one another despite beingsubject to interference caused by TV signal 402.

In one embodiment, nodes 130 may also implement some or all of thefunctionality previously described as being performed by server 154. Forexample, a given node 130 could communicate with TVWS database 410 todetermine a set of available channels at a particular location as wellas transmitter settings associated with any nearby TV towers. The givennode 130 could then implement the techniques described in conjunctionwith FIG. 5, or a simplified version of those techniques, and thendetermine new operating parameters with which future communicationsshould be performed. The simplified version of those techniques couldinclude accessing a look-up table indexed based on interference levelsthat provides specific operating parameters corresponding to specificinterference levels.

Nodes 130 may also modify existing operating parameters based on dataretrieved from TVWS database 410 that reflects the operation of otherTVWS devices not included within network 102, including the location ofthose devices, power settings, modulation settings, data rates,occupancy, duty cycles, synchronization between those devices, or othersuch information. Nodes 130 may also cooperate with one another todetermine common operating parameters with which to communicate based onduty cycle, communication protocol, power levels, and so forth.

In addition, nodes 130 may determine or modify operating parametersbased on data collected from a wide variety of sources beyond TVWSdatabase 410. For example, a given node 130 may determine the locationand various settings associated with TV tower 402 by retrieving thatinformation from other public sources via the Internet. Persons skilledin the art will understand that such information is widely available tothe general public and may be acquired by nodes 130 via any technicallyfeasible means. In general, nodes 130 may operate independently ofserver 154 and may not be required to interact with server 154 toacquire information pertaining to TV towers and the associated settings.In other words, nodes 130 may be configured to connect to the Internetand gather TV tower information autonomously.

Each node 130 may also be preconfigured to include a dataset thatspecifies the location and settings associated with particular TVtowers. Instead of acquiring that information via external sources, suchas the TVWS database 410 or public sources accessed across the Internet,a given node 130 may simply query the preconfigured dataset anddetermine/modify operating parameters based on that data. The datasetcould be added to memory associated with each node 130 duringmanufacture, among other possibilities.

As previously mentioned, server 154 may communicate with optimizeddatabase 420 in order to retrieve QOS metrics for available channels atspecific locations. Server 154 may determine operating parameters fornodes 130 based on the QOS metrics associated with those availablechannels. The QOS metric for a particular channel and particularlocation generally indicates the quality of that channel at thatlocation, and, specifically, may indicate a packet loss rate associatedwith the channel and location or other specific types of quality metricsor combinations of quality metrics.

For example, the QOS metric for a channel and location could indicate anexpected interference level associated with the channel and location andcould be derived based on the inverse of the expected interferencelevel. That interference level could be computed by implementing theaforementioned power loss modeling techniques, or could be derived frominterference measurements performed by nodes 130 residing near thelocation.

Alternatively, the QOS metric for the channel and location couldindicate the number of other TVWS devices currently operating on thatchannel and/or information describing those TVWS devices. In such acase, the QOS metric for the channel could have a lower value when thechannel is currently occupied by a large number of TVWS devices.Similarly, the QOS metric for the channel could have a lower value whenthe channel is currently occupied by any number of TVWS devices thatrequire a significant amount of bandwidth, such as, e.g., TVWS devicesthat support multimedia streaming.

The QOS metric for a channel and location could also be derived from anycombination of different factors, including expected interference levelsdue to nearby TV towers, expected interference levels due to other TVWSdevices, expected bandwidth available within the channel, reliability ofthe channel, flux of TVWS devices through the location, and so forth.

Optimized database 420 may have a wide range of different entries thatreflect the QOS metrics associated with various channels and locations.In addition, optimized database 420 may have multiple different entriesthat reflect the QOS metric for a particular location and particularchannel. For example, optimized database 420 could have an entry thatreflects a QOS metric for a particular channel and location that isderived by implementing the power loss modeling techniques describedabove. Additionally, optimized database 420 could also include otherentries that each reflects a measured QOS metric for the particularchannel and particular location, as reported by nodes 130. An exemplarydatabase table within optimized database 420 that reflects differentexemplary entries is described in greater detail below in conjunctionwith FIG. 7.

FIG. 7 is a conceptual diagram that illustrates an exemplary table 700in optimized database 420 shown in FIG. 4 that includes quality ofservice metrics for channels on which nodes 130 of FIG. 4 maycommunicate, according to one embodiment of the present invention. Asshown, table 700 includes a set of columns and a set of rows. Thecolumns of table 700 include a primary key (PK) column 702, a latitudecolumn 704, a longitude column 706, a channel column 708, a quality ofservice column 710, a node identifier (nodeID) column 712, and atimestamp column 714. The rows of table 700 correspond to differententries within that table, and include entries 720, 721, and 722 through720+N.

A given entry includes a PK value that represents a unique identifierfor the entry within table 700, latitude and longitude values thatrepresent a particular location on the surface of the Earth, a channelthat may represent a range of frequencies or a frequency hoppingsequence, and a QOS value. The QOS value represents the quality of thechannel at the particular location. The given entry may also include anodeID in situations where the QOS value associated with the entry wascomputed and reported by a node 130. The nodeID may be “null” when theQOS value is not associated with a particular node 130, such as, e.g.,in situations where the QOS value is derived based on the power lossmodeling approach previously described. The given entry may also includea timestamp that reflects a time when the entry was added to table 700or a time when the QOS was computed. In one embodiment, an entry oftable 700 includes multiple different timestamps that could reflect, forexample, a time when the entry was added, a time when the QOS wascomputed, a time when the QOS was updated, or any other relevant times.

Persons skilled in the art will understand that table 700 is describedherein for exemplary purposes only and that the various columnsassociated with table 700 may vary in practice. In general, optimizeddatabase 420 may be structured according to a wide variety of differentdatabase schemas and may include multiple different tables. Accordingly,the various approaches discussed herein may be applicable to any tableor tables within optimized database 420.

Referring back now to FIG. 4, nodes 130 may repeatedly report measuredQOS metrics for different channels and locations to server 154, andserver 154 may, in turn, cause optimized database 420 to generateadditional entries that reflect these newly-measured QOS metrics. Nodes130 may also simply report QOS metrics directly to optimized database420 without interacting with server 154. With this approach, optimizeddatabase 420 may include up-to-date entries that reflect the QOS metricsfor different TVWS channels at a variety of different locations. Insituation where the expected interference levels (i.e. those computedbased on power loss modeling) diverge from the actual interferencelevels, optimized database 420 may include entries that reflect theactual interference levels. For example, the expected interferencelevels proximate to TV tower 400 may be quite high, although the actualinterference levels proximate to TV tower 400 within the walls of abuilding may be quite low. Optimized database 420 may include entriesthat reflect the actual interference levels.

Based on the information stored within optimized database 420, as wellas that stored within TVWS database 410, server 154 is capable ofdetermining operating parameters for the nodes 130. In one embodiment, agiven node 130 may request new operating parameters from server 154, andserver 154 may then retrieve a set of entries from optimized database420 that are associated with the location of the given node 130. Server154 may process those entries and determine new operating parameters,including one or more channels with which the given node 130 shouldimplement for future communications, among other things. Server 154 maythen transmit the operating parameters to the given node 130. Inresponse, the given node 130 may interact with TVWS database 410 inorder to determine which, if any, of the one or more channels associatedwith the new operating parameters are available for use. The given node130 may then select an available channel from the one or more channelson which to perform future communications. The given node 130 may alsoimplement the new operating parameters to perform future communicationswith a particular sensitivity, signal to noise ratio, and so forth.

In another embodiment, server 154 may act as a proxy mechanism for nodes130. A given node 130 may request new operating parameters from server154, and server 154 may then interact with TVWS database 410 on behalfof the given node 130 in order to determine which channels are availableat the location occupied by the given node 130. Server 154 may thenretrieve a set of entries from optimized database 420 that areassociated with the location of the given node 130 and with the channelsthat are available at that location. Server 154 may process thoseentries and determine new operating parameters, including one or morechannels, with which the given node 130 should implement for futurecommunications. Server 154 may then transmit the operating parameters tothe given node 130. In response, the given node 130 may implement thenew operating parameters to perform future communications on aparticular channel with a particular sensitivity, signal to noise ratio,and so forth.

In either of the two embodiments discussed above, server 154 isconfigured to update optimized database 420 to reflect informationderived from TVWS database 410. For example, if server 154 determinesthat a given channel is currently in use by a significant number ofother TVWS devices (i.e. based on information provided by TVWS database410), then server 154 may add an entry to optimized database 420 thatreflects a low QOS metric for that channel. Server 154 may also updateoptimized database 420 to include entries indicating low QOS metrics (orQOS metrics of zero) for channels that are not available in certainregions.

When determining operating parameters for different nodes 130, server154 is configured to account for the specific requirements of thosedifferent nodes 130. For example, a node 130 could request a channelwith high bandwidth and a low error rate, and server 154 could providethat node with operating parameters that reflect a channel with a highQOS metric. In this example, the node 130 could be a multimedia deviceconfigured to stream audio and video data across the portion 412 of thenetwork.

Server 154 may also allocate different channels to different groups ofnodes 130 according to the requirements of those different groups ofnodes 130. For example, server 154 could allocate a high-QOS channel tonodes 130 that require a low error rate, while allocating a low-QOSchannel to nodes 130 with less stringent error rate requirements. Thesedifferent groups of nodes 130 may represent different portions ofnetwork 102 or may be configured to interoperate on a particularchannel. Alternatively, server 154 may determine groups of nodes 130that have diverse requirements and then allocate different channels toeach such group. A given group may include a balanced collection ofnodes 130 with both high-QOS requirements and low-QOS requirements.Sever 154 is configured to perform any technically feasible groupingprocedure and/or resource allocation procedure to generate groups ofnodes 130 and to allocate channels to those groups.

When interacting with optimized database 420, server 154 may execute awide variety of different queries, with widely varying complexity,against optimized database 420 in order to retrieve relevant entrieswhen servicing a particular request from a node 130. Server 154 may alsoprocess entries returned for a given query in order to select a channelfor the requesting node 130. For example, server 154 could queryoptimized database 420 for entries associated with a particular locationand having a threshold QOS metric. Then, server 154 could process thereturned entries to identify a channel with minimal variation of QOSmetric across different entries associated with that channel. Personsskilled in the art will understand that such post-processing of returnedentries may vary widely based on the specific requirements of therequesting node 130.

As mentioned above, any given node 130 may implement some or all of thefunctionality described as being performed by the server 154. In somesituations, a node 130 may operate autonomously and may have limitedinteraction with server 154. In such situations, the node 130 may accessTVWS database 410, optimized database 420, generate QOS metrics andreport those metrics to optimized database 420, determine and/or modifyoperating parameters, and so forth, without interacting with server 154.

Persons skilled in the art will recognize that the approaches describedabove may be applied to nodes 130 that reside within any technicallyfeasible class of network beyond a wireless mesh network. For example,nodes 130 may reside within a star network or personal area network(PAN) and implement the different approaches described herein.Additionally, the approaches described thus far may be implemented tomitigate interference caused by a wide variety of different types ofdevices beyond TV towers. For example, nodes 130 may reside within anetwork having a tiered priority system (a tiered network). In a tierednetwork, high-priority devices may have a higher transmit power, or morerelaxed out-of-band transmit rules compared to nodes 130. The prioritiesof the different devices in the network may be derived from specificlicensing agreements that regulate the operation of those devices. Nodes130 may be configured to mitigate interference caused by higher-prioritydevices within that network by implementing the approaches describedherein. A tiered network could be, for example, the T108 network inJapan. In the context of the T108 network, a node configured to transmitat 20 milliwatts (mW) could implement the disclosed techniques in orderto mitigate interference caused by a higher-priority device configuredto transmit at 250 mW.

By implementing the different approaches described herein, eitherindependently or in conjunction with one another, server 154 and/ornodes 130 may determine operating parameters for nodes 130 that allowthose nodes to communicate despite interference. Accordingly, thevarious approaches described may allow nodes within a network, such aswireless mesh network 102 shown in FIG. 1, to reside substantiallycloser to a source of interference, such as TV tower 400, whilemaintaining reliable communication. The different techniques discussedthus far are described in greater detail below in conjunction with FIGS.8-10.

FIG. 8 is a flow diagram of method steps for estimating the level ofinterference caused by TV signal 402 of FIG. 4, according to oneembodiment of the present invention. Although the method steps aredescribed in conjunction with the systems of FIGS. 1-7, persons skilledin the art will understand that any system configured to perform themethod steps, in any order, is within the scope of the presentinvention.

As shown, a method 800 begins at step 802, where server 154 receives arequest for operating parameters from a node 130, such as node 130-7 or130-8. The request may also indicate a specific use-case associated withthe node 130. For example, the request could indicate that the node 130supports multimedia streaming and is requesting operating parametersthat would support that functionality.

At step 804, server 154 retrieves TV tower data from TVWS database 410.The TV tower data may reflect a set of available channels in a regionproximate to the node 130 as well as power and frequency settingsassociated with one or more TV towers proximate to that node, includingTV tower 400.

At step 806, server 154 computes the power loss of TV signal 402 due tofrequency separation between TV signal 402 and a frequency at which anode 130 may communicate. Server 154 may perform step 802 byimplementing the power loss modeling technique described in conjunctionwith graph 600 shown in FIG. 6.

At step 808, server 154 computes the power loss of TV signal 402 due tophysical separation between TV tower 400 and the node 130. The physicalseparation could be, e.g., distance 414 or 416 shown in FIG. 4. Server154 may perform step 802 by implementing the power loss modelingtechnique described in conjunction with graph 640 shown in FIG. 6.

At step 810, server 154 computes the expected interference level at thenode 130 due to TV signal 402 by combining the power loss computed atstep 804 with that computed at step 806. In one embodiment, server 154computes the expected amount of interference as: interference=initialpower of TV signal 402−power loss due to frequency separation−power lossdue to physical separation.

At step 812, server 154 determines operating parameters for the node 130based on the expected interference level due to TV signal 402. Theoperating parameters determined for the node 130 may include a selectedchannel on which to communicate, a particular sensitivity with which toprocess received signals, a target signal-to-noise ratio implemented fora signal to be transmitted, or other parameters that may influence thequality and strength of signals involved with communication with othernodes 130. At step 814, the server 154 transmits the operatingparameters to the node 130. The node 130 may then perform communicationsaccording to those operating parameters. The method 800 then ends. Withthis approach, server 154 is configured to determine operatingparameters for the node 130 that may mitigate interference caused by TVsignal 402.

In one embodiment, the node 130 may also implement some or all of themethod 800. For example, the node 130 could performs step 804 andcommunicate with TVWS database 410 to determine a set of availablechannels at a particular location as well as transmitter settingsassociated with any nearby TV towers. The node 130 could then performsteps 806, 808, 810, and 812, or a simplified version of thosetechniques, and then determine new operational settings with whichfuture communications should be performed. The simplified version ofthose techniques could include accessing a look-up table indexed basedon interference levels that provides specific operational settingscorresponding to specific interference levels.

Server 154 may also determine operating parameters for nodes 130 basedon QOS metrics retrieved from optimized database 420. Server 154 maythen update optimized database 420 based on QOS metrics reported bynodes 130, as described in greater detail below in conjunction with FIG.9.

FIG. 9 is a flow diagram of method steps for updating optimized database420 of FIG. 4 to reflect QOS metrics received from one of nodes 130 ofFIG. 4, according to one embodiment of the present invention. Althoughthe method steps are described in conjunction with the systems of FIGS.1-7, persons skilled in the art will understand that any systemconfigured to perform the method steps, in any order, is within thescope of the present invention.

As shown, a method 900 begins at step 902, where server 154 receives arequest for operating parameters from a node 130 that resides at a firstlocation. At step 904, server 154 retrieves one or more entriesassociated with the first location from optimization database 420.Server 154 may also retrieve the one or more entries based on a minimumQOS metric required by the node 130 or other requirements associatedwith the node 130.

At step 906, server 154 determines operating parameters for the node 130based on the QOS metric associated with each available channelassociated with the first location. Server 154 could, for example,simply select the channel having the highest QOS metric, then determineoperating parameters for the nodes 130 based on the selected channel.

At step 908, server 154 transmits the operating parameters to the node130. The node 130 may then perform a reconfiguration process based onthose operating parameters and then perform future communicationsaccording to those operating parameters. The node 130 may also performvarious measurements in order to determine a QOS metric for the channelassociated with the operating parameters received from server 154, andthen transmit that QOS metric to server 154.

At step 910, server 154 receives a QOS metric from the node 130 for thechannel associated with the operational parameters. The QOS metric mayrepresent a more current representation of the QOS of that channel thanis present in optimized database 420. At step 912, server 154 updatesoptimized database 420 to reflect the QOS metric. The method 900 thenends.

With this approach, server 154 may update optimized database 420 toinclude up-to-date entries that reflect the QOS metrics for differentTVWS channels at a variety of different locations.

FIG. 10 is a flow diagram of method steps for reconfiguring one of nodes130 of FIG. 4 to mitigate the interference caused by TV signal 402 ofFIG. 4, according to one embodiment of the present invention. Althoughthe method steps are described in conjunction with the systems of FIGS.1-7, persons skilled in the art will understand that any systemconfigured to perform the method steps, in any order, is within thescope of the present invention.

As shown, a method 1000 begins at step 1002, where a node 130 transmitsa request for operating parameters to server 154. The node 130 may besubject to interference caused by, e.g., TV signal 402. At step 1004,the node 130 receives new operating parameters from server 154. At step1006, the node 130 performs a reconfiguration in order to operateaccording to the operating parameters. In doing so, the node 130 mayswitch channels and proceed to communicate on a channel specified by theoperating parameters. The node 130 may also communicate with aparticular sensitivity, signal-to-noise ratio, and other operatingparameters.

At step 1008, the node 130 determines a QOS metric for the channelassociated with the operating parameters. The QOS metric may represent,for example, a packet loss rate, among other quality metrics associatedwith wireless communication. At step 1010, the node 130 transmits theQOS metric to server 154.

With this approach, nodes 130 may repeatedly report measured QOS metricsfor different channels and locations to server 154. Server 154 may thenupdate optimized database 420 accordingly, as described above inconjunction with FIG. 9. Optimized database 420 may thus includeup-to-date entries that reflect the QOS metrics for different TVWSchannels at a variety of different locations.

In sum, nodes within a network are configured to communicate with oneanother on one or more television white space (TVWS) frequencies thatmay be subject to interference caused by nearby TV towers. In order tomitigate that interference, the nodes may be configured to communicateaccording to specific operating parameters. The operating parameters maybe generated based on expected interference levels caused by the nearbyTV towers or QOS metrics associated with available channels. The nodesmay also update a private database to reflect the expected interferencelevels or measured QOS metrics for different channels.

Advantageously, a network of nodes is configured to perform wirelesscommunications within a TVWS spectrum despite interference that may becaused by nearby TV towers. In addition, those nodes are configured toupdate the private database so that other nodes may determine operatingparameters that mitigate that interference.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof. For example, aspects of thepresent invention may be implemented in hardware or software or in acombination of hardware and software. One embodiment of the inventionmay be implemented as a program product for use with a computer system.The program(s) of the program product define functions of theembodiments (including the methods described herein) and can becontained on a variety of computer-readable storage media. Illustrativecomputer-readable storage media include, but are not limited to: (i)non-writable storage media (e.g., read-only memory devices within acomputer such as CD-ROM disks readable by a CD-ROM drive, flash memory,ROM chips or any type of solid-state non-volatile semiconductor memory)on which information is permanently stored; and (ii) writable storagemedia (e.g., floppy disks within a diskette drive or hard-disk drive orany type of solid-state random-access semiconductor memory) on whichalterable information is stored. Such computer-readable storage media,when carrying computer-readable instructions that direct the functionsof the present invention, are embodiments of the present invention.

In view of the foregoing, the scope of the present invention isdetermined by the claims that follow.

The invention claimed is:
 1. A computer-implemented method forconfiguring a node to communicate on a television white space (TVWS)spectrum of frequencies, the method comprising: receiving, at a server,a request for at least one operating parameter from a first node thatresides at a first location in a network; retrieving, from a firstdatabase, a list of one or more TVWS channels available at the firstlocation; in response to retrieving the list of one or more TVWSchannels from the first database, retrieving, from a second database,one or more quality of service metrics based on the list of one or moreTVWS channels retrieved from the first database, wherein the seconddatabase is different from the first database; determining the at leastone operating parameter for the first node based on the one or morequality of service metrics; and transmitting the at least one operatingparameter to the first node, wherein the at least one operatingparameter transmitted to the first node includes a sensitivity valuethat is used by the first node to process one or more signals receivedon a first available TVWS channel, and the first node is configured toperform future communications over the first available TVWS channelaccording to the at least one operating parameter.
 2. Thecomputer-implemented method of claim 1, further comprising: receivingfrom the first node a first quality of service metric associated withthe first available TVWS channel and the first location; and updatingthe second database to include an entry that includes the first qualityof service metric, the first available TVWS channel, and the firstlocation.
 3. The computer-implemented method of claim 1, furthercomprising: receiving the at least one operating parameter; configuringa network interface associated with the first node to communicate overthe first available TVWS channel according to the at least one operatingparameter; generating a first quality of service metric associated withcommunication operations performed over the first available TVWSchannel; and transmitting the first quality of service metric to theserver.
 4. The computer-implemented method of claim 1, wherein the atleast one operating parameter transmitted to the first node furtherincludes a target signal-to-noise ratio with which signals are to betransmitted by the first node over the first available TVWS channel. 5.The computer-implemented method of claim 1, wherein a first quality ofservice metric associated with the first available TVWS channel reflectsa packet loss rate associated with the first available TVWS channelpreviously measured by a node configured to communicate over the firstavailable TVWS channel at the first location.
 6. Thecomputer-implemented method of claim 1, wherein a first quality ofservice metric associated with the first available TVWS channel reflectsthe inverse of an expected interference level associated with the firstavailable TVWS channel at the first location.
 7. Thecomputer-implemented method of claim 6, further comprising generatingthe expected interference level by: computing a first power lossassociated with a TV signal based on frequency separation between afrequency associated with the first available TVWS channel and afrequency associated with a channel on which a TV tower transmits the TVsignal; computing a second power loss associated with the TV signalbased on physical separation between a location associated with the TVtower and the first location; and reducing an initial power levelassociated with the TV signal by the first power loss and by the secondpower loss.
 8. The computer-implemented method of claim 7, furthercomprising: retrieving the frequency associated with the channel onwhich the TV tower transmits the TV signal, the location associated withthe TV tower, and the initial power level associated with the TV signalfrom a third database, wherein the third database comprises a publicdatabase, and wherein the second database comprises a private database.9. The computer-implemented method of claim 7, wherein the first powerloss is computed based on a frequency loss model, and the second powerloss is computed based on a path loss model.
 10. Thecomputer-implemented method of claim 1, wherein a first quality ofservice metric is derived from a power loss model and a second qualityof service metric is reported by a node at the first location.
 11. Thecomputer-implemented method of claim 1, wherein a first quality ofservice metric is determined based on a combination of a first factorand a second factor, and a second quality of service metric isdetermined based on a combination of a third factor and a fourth factor.12. The computer-implemented method of claim 1, wherein a first qualityof service metric associated with the first available TVWS channelindicates an expected available bandwidth for the first available TVWSchannel at the first location.
 13. The computer-implemented method ofclaim 1, wherein a first quality of service metric associated with thefirst available TVWS channel indicates a flux of TVWS devices throughthe first location.
 14. The computer-implemented method of claim 1,wherein the server updates the second database based on informationretrieved from the first database.
 15. One or more non-transitorycomputer-readable media storing program instructions that, when executedby one or more processing units, cause the one or more processing unitsto configure a node to communicate on a television white space (TVWS)spectrum of frequencies, by performing the steps of: receiving, at aserver, a request for at least one operating parameter from a first nodethat resides at a first location in a network; retrieving, from a firstdatabase, a list of one or more TVWS channels available at the firstlocation; in response to retrieving the list of one or more TVWSchannels from the first database, retrieving, from a second database,one or more quality of service metrics based on the list of one or moreTVWS channels retrieved from the first database, wherein the seconddatabase is different from the first database; determining the at leastone operating parameter for the first node based on the one or morequality of service metrics; and transmitting the at least one operatingparameter to the first node, wherein the at least one operatingparameter transmitted to the first node includes a sensitivity valuethat is used by the first node to process one or more signals receivedon a first available TVWS channel, and the first node is configured toperform future communications over the first available TVWS channelaccording to the at least one operating parameter.
 16. The one or morenon-transitory computer-readable media of claim 15, further comprisingthe steps of: receiving from the first node a first quality of servicemetric associated with the first available TVWS channel and the firstlocation; and updating the second database to include an entry thatincludes the first quality of service metric, the first available TVWSchannel, and the first location.
 17. The one or more non-transitorycomputer-readable media of claim 15, further comprising the steps of:receiving the at least one operating parameter; configuring a networkinterface associated with the first node to communicate over the firstavailable TVWS channel according to the at least one operatingparameter; generating a first quality of service metric associated withcommunication operations performed over the first available TVWSchannel; and transmitting the first quality of service metric to theserver.
 18. The one or more non-transitory computer-readable media ofclaim 15, wherein the at least one operating parameter transmitted tothe first node further includes a target signal-to-noise ratio withwhich signals are to be transmitted by the first node over the firstavailable channel.
 19. The one or more non-transitory computer-readablemedia of claim 15, wherein a first quality of service metric associatedwith the first available TVWS channel reflects a packet loss rateassociated with the first available TVWS channel previously measured bya node configured to communicate over the first available TVWS channelat the first location.
 20. The one or more non-transitorycomputer-readable media of claim 15, wherein a first quality of servicemetric associated with the first available TVWS channel reflects theinverse of an expected interference level associated with the firstavailable TVWS channel at the first location.
 21. The one or morenon-transitory computer-readable media of claim 20, further comprisinggenerating the expected interference level by: computing a first powerloss associated with a TV signal based on frequency separation between afrequency associated with the first available TVWS channel and afrequency associated with a channel on which a TV tower transmits the TVsignal; computing a second power loss associated with the TV signalbased on physical separation between a location associated with the TVtower and the first location; and reducing an initial power levelassociated with the TV signal by the first power loss and by the secondpower loss.
 22. The one or more non-transitory computer-readable mediaof claim 21, further comprising: retrieving the frequency associatedwith the channel on which the TV tower transmits the TV signal, thelocation associated with the TV tower, and the initial power levelassociated with the TV signal from a third database, wherein the thirddatabase comprises a public database, and wherein the second databasecomprises a private database.
 23. The one or more non-transitorycomputer-readable media of claim 21, wherein the first power loss iscomputed based on a frequency loss model, and the second power loss iscomputed based on a path loss model.
 24. A system for configuring a nodeto communicate on a television white space (TVWS) spectrum offrequencies, including: one or more processing units that reside withina server and are configured to: receive a request for at least oneoperating parameter from a first node that resides at a first locationin a network, retrieve, from a first database, a list of one or moreTVWS channels available at the first location, in response to retrievingthe list of one or more TVWS channels from the first database, retrieve,from a second database, one or more quality of service metrics based onthe list of one or more TVWS channels retrieved from the first database,wherein the second database is different from the first database,determine the at least one operating parameter for the first node basedon the one or more quality of service metrics, and transmit the at leastone operating parameter to the first node, wherein the at least oneoperating parameter transmitted to the first node includes a sensitivityvalue that is used by the first node to process one or more signalsreceived on a first available TVWS channel, and the first node isconfigured to perform future communications over the first availableTVWS channel according to the at least one operating parameter.
 25. Thesystem of claim 24, further including: one or more memory units coupledto the one or more processing units and storing program instructionsthat, when executed by the one or more processing units, cause the oneor more processing units to: receive the request for the at least oneoperating parameter, retrieve the list of the one or more TVWS channelsavailable at the first location from the first database, retrieve theone or more quality of service metrics for the one or more TVWS channelsindicated in the list retrieved from the first database from the seconddatabase, determine the at least one operating parameter for the firstnode based on the one or more quality of service metrics, and transmitthe at least one operating parameter to the first node.
 26. Acomputer-implemented method performed by a node for configuring the nodeto communicate on a television white space (TVWS) spectrum offrequencies, the method comprising: transmitting to a server, by a firstnode that resides at a first location in a network, a request for atleast one operating parameter; receiving from the server, at the firstnode, at least one operating parameter for the first node determinedbased on a list of one or more TVWS channels available at the firstlocation retrieved from a first database, and based on one or morequality of service metrics retrieved, in response to retrieving the listof one or more TVWS channels from the first database, from a seconddatabase based on the list of one or more TVWS channels retrieved fromthe first database, wherein the second database is different from thefirst database, and the at least one operating parameter received at thefirst node includes a sensitivity value that is used by the first nodeto process one or more signals received on a first available TVWSchannel; and configuring, by the first node, a transceiver within thefirst node to perform future communications over the first availableTVWS channel according to the at least one operating parameter.
 27. Thecomputer-implemented method of claim 26, wherein a quality of servicemetric associated with a given TVWS channel reflects an inverse of anexpected interference level associated with the given TVWS channel atthe first location.
 28. The computer-implemented method of claim 26,wherein the first database resides external to the first node at asecond location within the network.
 29. The computer-implemented methodof claim 26, wherein the server is preconfigured to include the firstdatabase, and wherein the first database includes location andtransmitter settings associated with a set of television (TV) towers.